Fixed bug that occurred when process with a 'count' signal returned empty data (data=[])

Author: balis

engine2/index.js

@@ -191,6 +191,8 @@ Engine.prototype.emitSignals = function(sigs, cb) {
     async.each(sigs, function iterator(sig, doneIter) {
         var sigInstances = [];
         sig._ts = timeStamp;
+        // FIXME: if there is no 'data', a "pure-metadata" signal will be sent. However, if there is a 'data=[]' (empty),
+        // no signals will be sent! It seems to work well with the semantics of 'count' signals, but should be tested
         if (sig.data) { // there is a 'data' array which may contain multiple instances of this signal
             for (var i in sig.data) {
                 var s = copySignal(sig);

engine2/process.js

@@ -358,22 +358,24 @@ var ProcLogic = function() {
             var countSigId = proc.fullInfo.outcounts && 
                 proc.fullInfo.outcounts[funcOuts[i]] ? proc.fullInfo.outcounts[funcOuts[i]]: undefined;
             if (countSigId) {
-                var count = outValues[i].data ? outValues[i].data.length: 1;
+                var count = outValues[i].data ? outValues[i].data.length: 1; 
                 var sigId = countSigId.split(":")[1]; 
 
                 //onsole.log("FUNC OUTS", funcOuts);
                 //onsole.log("EMITTING COUNT SIG", sigId);
                 //onsole.log("IN  COUNTS", proc.fullInfo.incounts);
                 //onsole.log("OUT COUNTS", proc.fullInfo.outcounts);
                 var sigV = {"_id": +sigId, "count": count, "control": "count", data: [{}]};
-                if (!proc.fullInfo.ordering) {
-                    proc.engine.emitSignals([sigV]);
-                } else {
-                    // TODO: test thouroughly if ordering works correctly with output "count" signals
-                    function Arg() {} // we need an Array-like object
-                    Arg.prototype = Object.create(Array.prototype);
-                    proc.emitStash[firingId] = new Arg;
-                    proc.emitStash[firingId].push(sigV); 
+                if (count > 0) { // 0 can happen if process returns an empty "data" array
+                    if (!proc.fullInfo.ordering) {
+                        proc.engine.emitSignals([sigV]);
+                    } else {
+                        // TODO: test thouroughly if ordering works correctly with output "count" signals
+                        function Arg() {} // we need an Array-like object
+                        Arg.prototype = Object.create(Array.prototype);
+                        proc.emitStash[firingId] = new Arg;
+                        proc.emitStash[firingId].push(sigV); 
+                    }
                 }
             }
         }